Endocrine Abstracts

Introduction: Gilbert syndrome is one of the most common inherited diseases, with a prevalence of 5–7%. It is caused by a mutation in UGT1A1 gene, which is in turn responsible for a deficiency in bilirubin glucuronidation. It courses with unconjugated hyperbilirubinemia, and jaundice may occur in adolescence, after fasting, exercise, or in menses, and also with certain drugs. Individuals with Gilbert syndrome seem to have a reduction in the prevalence of micro- and macrovascular complications due to the anti-oxidant effects of bilirubin.

Clinical case: A 20-year-old male patient, smoker, with type 1 diabetes mellitus diagnosed at the age of 6 and long standing poor metabolic control. He had a history of episodes of mild jaundice that had never been valued by the patient. Despite the poor compliance to diet and insulin therapy, with persistent poor glycemic control, he had no target organ complications. The patient was hospitalized in the Endocrinology Department for significant glycemic instability. A1c on admission was 10.7%. During hospitalization, gastroenterological advice was requested for persistent unconjugated hyperbilirubinemia (total bilirubin 28.5 mg/l, direct bilirubin 5.1 mg/l) without hemolytic disease or liver dysfunction. The diagnosis of Gilbert syndrome was then made. The patient’s microalbuminuria was 12.65 mg/24 h (<30 mg/24 h). Retinopathy was excluded.

Discussion: It has been recently documented a lower prevalence of vascular complications in patients with diabetes mellitus and Gilbert syndrome, as well as reduced markers of oxidative stress and inflammation. Bilirubin appears to have an inhibitory effect on NADPH oxidase activity, which may be an important source of increased superoxide production in diabetic vascular tissues. It is possible that sustained hyperbilirubinemia inhibits oxidative stress and prevents vascular complications in patients with both diseases.